Re: Myself, RDF and HTML

Hello Toby Inkster -- and all.

I have been playing around (I do that more and more in my old age) with XHTML/RDFa  and have composed two exemplar pages ..........

http://jp29.org/testrdfa.php
http://jp29.org/rdfaprimer.php

.......... just to check out content negotiation serving and how a few RDFa attributes might be used. Nothing serious intended -- just a few ruminations.

James Pickering
Pickering Pages
http://jp29.org/
 
---- Toby A Inkster <tai@g5n.co.uk> wrote: 
> 
> Hello all,
> 
> First to quickly introduce myself, I'm Toby Inkster. I'm an in-house 
> developer for a UK charity, though my interest in the semantic web is not 
> really related to my day job.
> 
> I'm working on a GPL'ed "semantics extractor" (for want of a better 
> description) called Cognition. The ultimate aim is to make it into a 
> desktop tool with integrated browser, but for now I'm happy to just parse 
> stuff and export it in interesting formats. As input it supports various 
> microformats (native, non-GRDDL support), RDFa, eRDF, RDF/XML (linked to 
> with <link rel=meta>, or embedded in XHTML directly using namespaces or 
> within HTML comments) and has partial support for GRDDL.
> 
> Cognition: http://buzzword.org.uk/cognition/
> 
> (Should be releasing a new version soon with s/instanceof/typeof/ amongst 
> other changes.)
> 
> My interests lie within what I like to call the "mixed case semantic web": 
> unifying POSH/microformat data models with the more formal side of the 
> Semantic Web. Making sure that data extracted from one side is available 
> to the other. As an example of the kind of thing I mean, take a look at 
> <http://examples.tobyinkster.co.uk/hcard>, which is a hybrid example of 
> hCard and RDFa. It is correctly parsed by Cognition, and can be output as 
> vCard or RDF/XML.
> 
> Anyway, I popped my head into the beginning of the task force meeting on 
> IRC this afternoon, to check if it was open to the public, as I had an 
> idea I wanted to contribute for supporting RDFa in HTML (i.e. as opposed 
> to XHTML).
> 
> The problem as I understand is that xmlns:foo attributes are unusable in 
> HTML as they won't validate. Strictly, they won't validate against the  
> XHTML DOCTYPE either, but we cough and mumble and ignore that because the 
> W3C validator pretends that they're allowed.
> 
> Anyway, my idea is: RFC 2731 to the rescue! RFC 2731 was a technique 
> proposed by the Dublin Core lot to allow the use of CURIE-like prefixes 
> like "dc:" to be used for HTML <meta> elements.
> 
> For example, to define the prefix "dc" to point to the current Dublin Core 
> RDF vocab, you could use:
> 
>  <link rel="schema.dc" href="http://purl.org/dc/terms/">
> 
> And then the prefix could be used in <meta> elements like:
> 
>  <meta name="dc.creator" content="Toby Inkster">
> 
> If this technique for defining prefixes were to be allowed in RDF (though 
> I'd recommend replacing the dot separator with a colon) then RDF in HTML 
> becomes feasible. 
> 
> With RFC 2731 these prefixes are valid document-wide, but it would be 
> theoretically possible to extend RFC 2731 to allow prefixes to have a 
> scope (i.e. equivalent to xmlns attributes on non-root elements) by simply 
> following the general rules of RDFa:
> 
>  <div about="#thisSection">
>    <span rel="schema:dc" href="http://purl.org/dc/terms/"></span>
>    <h2 property="dc:title">Title of this Section</h2>
>    <!-- ... etc ... -->
>  </div>
> 
> if desired. However, that might be impractical to implement, because of 
> cases like this:
> 
>  <div about="#thisSection">
>    <h2 property="dc:title">Title of this Section</h2>
>    <!-- ... etc ... -->
>    <span rel="schema:dc" href="http://purl.org/dc/terms/"></span>
>  </div>
> 
> so I'd probably suggest restricting this technique to just allow prefixes 
> to be defined through <link> elements in the document head.
> 
> Anyway, those are my ideas with regards to RDFa in HTML. If anyone has any 
> queries then, let me know either on or off list.
> 
> By the way, according to the list archives there are mumbles about 
> changing the algorithm for parsing RDFa, particularly with regard to 
> "dangling rels". If this has been decided, could the rdfa-syntax document 
> be updated so that I can catch up?
> 
> regards
> 
> -- 
> Toby A Inkster BSc (Hons) ARCS
> 
>

Received on Thursday, 10 April 2008 18:36:01 UTC